Forging apparatus



Dec. 26, 1944. BENEs 2,365,857

FORGING APPARATUS Filed June 24, 1943 11 sheets-sheet 1 IF "MW 7 7 V V AH] .1?2 72/2 fan dds 0a)" 1 B672 65 (XL far; e; 176

Dec. 1944. G. P. BENES 2,365,857

FORGING APPARATUS Filed June 24, 1943 11 Sheets-Sheet 2 Jn'lfintor: adsMr P. Bane-s Dec. 26, 1944. BENEs 2,365,857

FORGING APPARATUS F iled June 24, 1943' 11 Sheets-Sheet 4 1944- e. P.BENES FORGING' APPARATUS Filed June 24, 1943 ll Sheets-Sheet 5 Dem26,1944. BENES 2,365,857

FORGING APPARATUS Filed June 24, 1943 11 Sheets-Sh eet 7 Dec. 26, 1944.GP. BENES FORG I NC: APPARATUS Filed June 24, 1943 11 Sheets-Sheet 8 iiij, y 32 Dec. 26, 1944. G. P. BENES FORGING APPARATUS Filed June 24, 1943ll Sheets-Sheet 9 W N a all? 1 m//// I.

a." m H E 3 1 A 7 ||x| m a u i,

j? pic ra fan 60.30/12 1 36/260 NN FN Dec. 26, 1944. P BENES 2,365,857

FORGING APPARATUS Filed June 24, 1943 ll Sheets-Sheet 10 jtforaz ya 11Sheets-Sheet 11 G. P. BENES FORGING APPARATUS Filed June 24, 1943 Dec.26, 1944.

g N FPN Patented Dec. 26, 1944 UNITED] STATES PATENT OFFICE 22 Claims.

This invention relates to forging apparatus and particularly to suchapparatus for forming punches, dies and the like by forging.

Many printing machines now in use employ printing devices upon which thetype characters of the text which is to be printed are formed asembossures. Such printing devices may be of many different forms such asthat disclosed in the Mohler Patent No. 1,812,894, patented July 7,1931, or in th Gollwitzer Patent No. 2,132,412, patented October 11,1938. Printing devices of the general character disclosed in theaforesaid patents include a rectangular carrier or frame with anembossable metal printing plate removably retained in position thereon,and in such printing devices, the type characters are embossed on theprinting plate so as to appear in the relief on the operative facethereof. Printing devices may also be of a one-piece construction in thegeneral form disclosed for example in the Duncan Patent No. 1,026,246,patented May 14, 1912, and in such instances the type characters areembossed in the metal of the one-piece printing device.

The type characters desired upon such printing devices or printingplates may be embossed thereon by means of an embossing machine such asthat illustrated in the Duncan Patent No. 1,518,904, patented December9, 1924, and in such an embossing machine the actual embossing operationis effected by pairs of punches and dies which are selected and operatedthrough an embossing operation in respect to each character which is tobe formed on the printin device or printing plate. v form and relationof the characters of the printed impression made from such printingdevice are dependent in a large measure upon the accuracy of form andrelationship of the punches and dies of the embossing machine, and toenable these punches and dies to be produced with the maxi mum ofaccuracy of form is an important object of this invention.

The punches and diesin such an embossing machine are of course subjectedto severe service in the course of which the working surfaces of thepunches and dies often become badly worn or deformed, thus makingreplacement thereof necessary. In the past. however, such replacement ofworn punches and dies has been relatively expensive primarily because ofthe cost of production of the punches and dies, and to enable these tobe economicall produced is another important object of this invention.Other objects related to the foregoing are to simplify the preparationof punches, dies and the like, and to accompl sh this in such a way thatthe punches and dies may be produced with the required accuracy of formand at a relatively high rate.

In the patent to Thompson No. 1,868,777, pat- The neatness and accuracyof ented July 26, 1932, an apparatus is disclosed wherein punches, diesand the like are produced by forging, and it is a further object of thisinvention to improve and simplify the mechanism for accomplishing suchforging operations. Other and further objects related to the foregoingare to simplify the loading and unloading of work blank in a machinewhich forges punches, dies and the like; to enable the operator of sucha machine to constantly and easily check and verify the operationalcharacteristics of such a machine so as to prevent damage to the work orto operative parts of the machines; and to improve and standardize thequality and accuracy of the work produced by such machines.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show a preferredembodiment and the principle thereof and what I now consider to be thebest mode in which I have contemplated applying that principle. Otherembodiments of the invention embodying the same or equivalent principlemay be used and structural changes may be made as desired by thoseskilled in the art without departing from the present invention and thepurview of the appended claims.

In the drawings:

Fig. 1 is a front elevational view illustrating a forging apparatusembodying the features of the invention; v

Fig. 2 isa side elevational view of the machine shown in Fig. 1';

Fig. 3 is a fragmental plan view of a portion of the apparatus shown inFigs. 1 and 2;

Fig. 4 is a fragmental vertical sectional view taken substantially alongthe line 4-4 of Fig. 3;

Fig. 5 is a fragmental vertical sectional view taken substantially alongthe line 55 of Fig. 3

Fig. 6 is a fragmental horizontal sectional view illustrating theheating chamber and therelationship of the electrodes to a workpiece;

Fig. '7 is a fragmental horizontal sectional view taken substantiallyalong the line l---! of Fig. 5;

Fig. 8 is a vertical sectional view taken along the line 8-8 of Fig. 5;

Fig. 9 is a fragmental elevational view as viewed from the line 9-9 inFig. 5;

Fig. 10 is a plan section taken substantially along the line IL -I 0 inFig. l;

Fig. 11 is a plan section taken substantially along the line I l--l I inFig. 4;

Fig. 12'is a fragmental elevational View showing the left hand side ofthe machine;

Fig. 13 is a View similar to Fig. 12 and showing the parts in differentpositions;

Fig. 14 is a fragmental vertical sectional view taken substantiallyalong the line I l|4 in Fig. 11;

trical and pneumatic control i n'echanisin 'of the machine;

Fig. is a perspective view of a punch of the character which isto *be formed by 'the 'r'nachine of;this invention; v I i Fig. 21 is aperspective view of a die which is adapte dffor cooperation bf the punch"'shown in Fig. "20 and which is adapted to 'be formed by the machine ofthis invention; and

Fig. 22 'is'a timing chart illustrating tamperating seduence and timing"of the various elementsof'the machine.

The machine 'of the present invention is particularly adapted for use vin forgingpunches such as that identified as :25 in 20 'of the drawings,or for the formation of dies such "as that indicated at 26 in 21. V Inthe formation of a punch as 25 f a rectangular "work blank substantiallyof the same shape as the "punch 25 isemployed. The ridtpnn the the slot21A, ew 'e a en i t fb j i hs time Of the forming or forgih'gfoperation.The blank from which thepun cih '25 is to'be ma d'eis first heated atorie'endthereof, and the heated end thereoi fis then forced with a 'forging blow into a master die whichfor msthe'desire d punch element 28thereon and a border "or base surfface "2 9 about th e bajse of thepunch element 23. fiihie punch element 28 as herein shown is arranged inthe 'foi'rn'of a capan letter L, and the die of Fig. 21 is shown asbeing adapted to cooperate with the punch 25 in formingsuch a letter Lonfa iprinting plate "or the like, The die 26 is similarly formed rrdm'ablank whi'ch'is generally rectangular in shape, but here again theformation of the die surfacesis'accomplished prior to the formation ofthe locating notch 21 and locating slot 21A. "Sucha work blank is heatedat one end thereof and "this hatedend is then forced with iaforgiifgst'r oke into'a master formingjdie which forms die recess 28A inthe heated end of the wori; blank. A border surface 29Ais formed aboutthe die'recess 28A in the aforesaid forgirigktroke, "and for certainuses, a pairof ridges 23Biniay befor'rne'din th'e same operation atopposite "ends ofythe base surface 29A. Ihe punch "25 and 'die 26constitute a cooperatingpairoi elements adapted for use in anembossingniachin'e 'sueh as that shown intheaforesaidpuncan Patent Nb.1,518,904, but it will be recognized that other form'sjof punches, diesor the like may also be formed through the use of the apparatus'iof t'hepresent invention.

In the form chosenfor disclosufe her'ein the invention is embodied inaforging machine 30 having a relatively large upstanding base 3| whichaffords a tabl'e 'top'32, and an upstanding frame structure 33 isrnounted on the "table top 32 to serve as a support a housing 34 w hifchforms a heating and forging chamber'35 jand the other related heatingand forging elements are supported 'on t he frame structure 33 inassociation with the housing 34. As shown in Figs. 1, 2, 4

and 12, the frame structure 33 is afforded by a pair of L-shapedcastings which serve as standards 36 and these standards 36 are disposedon the table top 32 on opposite sides of a clearance slot 31 formed inthe table top, and the arrangement is such that one of the arms of eachL- shaped member extends upwardly near the forward edge of the table top32 while the other arm 36A of each -L-shaped member extends in "arearward direction. As will be evident in Fig.

-1-2'of'the drawings, the L-shaped standards 36 are formed with centralwebs and with marginal flanges about these webs, and fastening bolts 38are passed through the lower flanges of the standards 36 to secure thestandards in position on the table top 32. Additional rigidity isafforded in the frame structure 33 through the provision of a mountingplate 33 which is rested upon the upper flanges of the rearwardlyextending portions of the standards 36 and is secured to the flange ofthese portions of the standards by means such as 'bolts 40. The mountingplate 39 also sertesas a support for'various elements of the mechanismas will hereinafter become evident.

As s hown in Fig. 1 of'the darwings, the'standerases are spaced apart ina lateral direction and the housing 34 extends across'the upper ends ofthe standards 36'so as't'o span the space there- 'and the housing '34 isheld in place on the upper ends of the "standards by means such as capscrews 4|. It is within the heating and forging ch'a'niber 'that thework blank, as W, is heated and then forged to the desired form, and for"use in accomplishing the "forging operation a inasterdie holder 43 anda work holder 44 are'adapt'e'd'to be supportedin opposed relation withinthe chamber 35 as shown in Fig. 4 of the drawings, the die holder 43being supported "at the top of theichamber 35in the preserit 'instan'c'eso as to face downwardly, while the work holder 44 is supported atthebottom of the chamber 35 'so as to face upwardly in alignment withthe die holder. 43. In order to afford such a relationship, the masterdie holder 43 is 'airranlged to be supported within an upstandingmountingsleeve '46 which is formed integralwith "the -walls of thehousing and into which 'acylindric'al supporting block 41 may beextended The supporting block 41 is arranged softhat'the 'di'e holder'43may be secured to the lowerend of the block/and thus when the block 41'is inserted downwardly 'into the mounting sleev' e4 6, the die holder43 will be disposed in the upperportion of the heating chamber35.

'In form herein shown the'die holder 43 comprises three separably'related plates within and between which a master die'50 maybe 10- cateda'n d positioned by the cooperative action of these three plates, theplates are secured in position on the lower end of the mounting blockmeans such as cap screws 5!. Thus, as shown-in Figs.4, 5,'and 7,themaster die holder 43inchid'es an upper 'plate"52 'which is disposedagainst the lower face of the mounting block 41 and which serves as astriking or abutment plate, an intermediate plate 53 which has a neatlyfitted opening 54 therethrough to receive the master die 50, and a lowerretaining'plate55 which engages the marginal edges of the lowerend'of'the master die andhas an entry opening Efi ther'ein through whicha heated work blan'l! W may be forced into operative engagement with theworking surfaces of the master die '50. If desired, the upper face ofthe plate 55 may be counterbored and the lower face of the plate 53 mayhave an extended neck about the opening 54 to afford a lateral interlockbetween the plates 53 and 56 to thereby accurately locate the entryopening 56 with respect to the working surfaces of the master die 50. Itwill be observed that the plate 53 is of a somewhat smaller diameterthan the plate 52, and an up wardly facing .shoulder is afforded withinthe sleeve 56 to cooperate with the plate 52 in limiting the downwardmovement of the mounting block 51. This arrangement assures the properlocation of the master die 56 in a vertical direction. The mountingblock 41 has a transverse slot 58 therein and the mounting block 4! is.held releasably in its lowermost position within the sleeve 46 by atransverse drive pin 59 which ex tends throughslots 60 in the oppositewalls of the sleeve 46 and through the slot 58 in the mounting block 47.The lower edge of the drive pin 59 has a sloping cam surface thereonwhich is adapted to engage the sloping bottom surface 6| of the slot 58so that by driving the pin 59 to the right in Fig. 4, the mounting blockM may be driven downwardly until the plate 52 is seated firmly upon theupwardly facing shoulder within the sleeve 46.

As shown in Fig. 4 of the drawings the work holder 54 is disposed in itsoperative position within the heating and forging chamber and to enableconvenient loading and unloading of Work blanks W in the work holder,means are provided which support the work holder for movement from itsoperative position of Fig. 4 to a forward loading position shown in Fig.13 of the drawings, and under the present invention this is accomplishedin such a way that during this movement back and forth between theloading position and the operative position, the work holder 44 ismaintained in substantially its normal relation to most of the otheroperative elements of the mechanism. In accomplishing this purpose, acarrier 65 is provided upon which the work holder 44 is mounted and thecarrier 65 is arranged for shifting movement to carry the work holder 44back and forth between its loading position and its operative position.As will. hereinafter be described in detail, the work holder 44 is notonly shiftable with the carrier 65 to the aforesaid loading position,but is also mounted on the carrier for longitudinal move ment through aforging stroke in an upward direction toward the master die 59, andunder the present invention the actuating means for driving the workholder M through such a forging stroke are also mounted on the carrier65 so as to be in their operative relation to the work holder 44 at alltimes. Such actuating means as herein shown are pneumatic in characterand for this reason an elongated cylinder 66 is provided which ispreferably utilized as a part of the carrier 65. 7 shown comprises theelongated cylinder 66 and a mounting sleeve 67 which is secured as bybolts 58 to the flanged upper end of the cylinder 66..

The carrier 55 is disposed between two standards 36 with the lowerportion of the cylinder 66 extending downwardly through the slot 37 inthe table top 32, and the carrier is supported by these standards sothat the desired shifting movement of the carrier 65 may be attained.Such shifting movement in the present instance is pivotal in character,and for this reason a pivotal mounting shaft H3 is extended Thus thecarrier 65 as herein between the two standards 36 and through a bearinglug 1| which is formed on the rear side of the cylinder 66 adjacent tothe upper end thereof as shown in Figs. 4, 5, 14, and 15. The shaft 10is rotatable in bearings 12 which are provided on the two standards 36,and the carrier is fixed to the shaft 10 by a set screw 13. When thecarrier is in the vertical or operative position shown in Fig. 4 of thedrawings, an upper portion thereof, which will be described in detailhereinafter, is engaged with the forward face of a stop plate 14 whichis bolted to the rear face of the housing 34 so as to extend downwardlytherefrom and act as a stop to determine the extent of rearward movementwhich may be imparted to the upper end of the carrier. The carrier 65 isnormally urged in a counterclockwise direction as viewed in Fig. 4toward the loading position of Fig. 13, and this is accomplished by aspring 15, Fig. 4, which acts between an anchoring rod 16 and a lug l7formed on the rear side of the cylinder 36 below the pivotal axis 16.

Thus, in order to place the carrier 65 in its operative position of Fig.4, the upper end of the carrier must be forced rearwardly against theaction of the spring 15 to the position of Fig. 4, and means areprovided for securing or looking the carrier in this operative position.For this purpose the mounting sleeve 6'! has a forwardly extendingbearing portion 17 through which a locking shaft 18 is extended parallelto the pivotal shaft 76 and spaced upwardly and forwardly a considerabledistance from the pivotal shaft 70. The locking shaft 18 is mounted inbearings 19 and is arranged to extend beyond the opposite sides of thebearing portion. H to positions located in front of the two standards36. For cooperation with the locking shaft it, a pair of looking plates80 are secured to the forward faces of the standards 36 as by means offlanges 8i and bolts 82, and these locking plates iili have locking andguiding slots 84 formed therein and centered upon the pivotal shaft in,the ends of the locking shaft 18 being arranged to extend through theselocking and guide slots 84. A pair of locking earns are secured on theshaft 18 as by pins 86, and these cams 85 are so positioned on the shaft18 as to ride in the locking and guiding slots 84. The locking cams 85are generally circular in form and are of such a di-- ameter that theymay be ro ated only when located within enlarged circular portions as ofthe slots 84, these enlarged portions 8 3- being formed at the upperends of the slots 55s.

The locking cams 85 are flattened on one side to afford two flatsurfaces 65 and 85" which are disposed at a slight angle to each otheras indicated at Fig. 15, and when the shaft 83 is rotated in acounterclockwise direction from the position shown in Fig. 15, the cams85 are so positioned that the flat surfaces 85 and 85 thereofsubstantially aligned with the outer edge surfaces of the slots 84. Whenthis relationship has been established, the carrier 65 may be rockedabout its pivot shaft 10 toward the forward loading position of Fig. 13so as to move the upper end thereof in a forward direction, and this isdone, the locking cams 85 move downwardly in the slots 84 to therelationship which is shown in dot-dash outline in 15. This loadingposition is determined by an upstanding stop S which is mounted on thetable top 32 in such a position as to lie in the path of the bearingportion 1'! of ends of the slots.

thecarrier. The height of the stop S is suchthat the cams '85 aremaintained out of contact with the lower ends of the slots '84 and thusthe faces of the cams 85 are not injured by striking the The shaft "I8is normally urged in a clockwise-direction toward the locking positionshown in Jig. 15 by a torsion spring 88 which surrounds the shaft l8 andacts between the shaft and the bearing portion ll. Thus when the carrierG is returned from its loading position against the action of the springl5 and to the operator wishes to release the lockingmeans, this a beaccomplished by actuation of a knurled operating head 89 which issecured by a'pin 90 to the right hand end of the locking shaft 28.

The holder 34 is in the nature of a. chuck having a plurality of jawsEdand S6, as shown in Fig. 10,

these jaws being so formed and related that they may be clamped aboutthe sidesof the lower portion of a work'blank W so as to support thework blank in an upwardly projecting relation wherein the upper sideedges of the work blank W may be engaged by the inner ends of a pair ofelectrodes H30, Fig. 5. The chuck jaws 95 and 96 are adapted to beoperated between their clamped and unclamped positions by meansincluding an operating handle ICE which is mounted on and extendsforwardly from the carrier 65, as will hereinafter be described indetail. When the work holder 4 is empty. the normal position thereof ina vertical sense is such that the carrier 65 may be rocked forwardly tothe loading position of Fig. 13, and during such movement the upperedges of the work holder and the associated holder 44 and as a result,the work blank W tends 'to strike the inner surfaces of the wall I03 ina forward withdrawing movement of the carrier I35. Because of this thework holder 44 is supported on the carrierby means of a shiftablelocating structure IE5 which provides an upper or advanced position inwhich it is shown in Fig. and a lower or retracted position wherein theupper end of a work blank W will clear the edge of the wall I33 in a foward rocking movement of the carrier 65.

As herein shown the locating structure I05 includes a locating sleeveI06 mounted within the sleeve 61 for limited sliding movement duringwhich the sleeve I06 is held against rotative movement by a stationarykey I01 mounted in the bearing block "ll and fitting into longitudinalgroove i053 formed in the forward side of the sleeve Hi6. The upwardmovement of the sleeve I05 is limited by an engagement of the sleevewith a plate I Ill which is secured across the upper end of the sleeve51 by means including bolts I I I. Downward movement of the sleeve I06is limited by engagement of a part mounted on the sleeve I00 with anannular shoulder I I2 formed by the upper end of the cylinder 66 asshown in Fig. 4. The locating sleeve N38 has the work holder 44 mountedtherein so that when the locating sleeve I96 is moved downwardly fromthe position shown in Fig. 4, the work holder 44 will be correspondinglywithdrawn in a downward direction;

enlarged head II6 formed onits lower end so as to engage the innersurface of the sleeve I06, and a plate II'I secured across the lower endof the sleeve I05 limits downward movement of the plunger I I5. A springI I8 surrounds the plunger "H 5 within the sleeve I06 and atits lowerend this sleeve acts upon the head I I6 through a bearing ring H9 tourge the plunger H5 downwardly, the upper end of the spring beingarrangedto bear against a pressure ring I which in turn bears against aninwardly directed annular flange Ill-2 formed at the upper end of thesleeve I06. The plunger H5 is maintained in a predetermined rotativerelation to the sleeve I06 by a key or spline I23 which is formed on thebottom plate III and extends upwardly within the sleeve I06 to engage acomplemented longitudinal groove I23 formed in the flange I I6 of theplunger.

At its upper end the plungerIIShas a reduced portion I25 at the lowerend of which an upwardly facing shoulder I26 is afforded and the jaws 95and 96 are disposed about the reduced portion I25 forelamping andunclamping movementand are held against relative rotative movement by .apin I21 which extends through the reduced portion I25 and engages atleast certain of the jaws 95 or 96. The desired clamping force isapplied to the several jaws 95 and 96 by an actuatin sleeve I30 whichhas inwardly tapered surfaces I3I adjacent it upper end which engagecomplemental '40 tapered inner surfaces on the upper portions of thechuck jaws 95 and 96. The arrangement is such that by imparting downwardmovement to the actuating sleeve I30, the jaws 95 and 06 may be actuatedtoward each other in afclamping direction.

This longitudinal movement of the actuating sleeve I30 is attained by athreaded lower portion I33 formed on the sleeveso as to engagecomplemental threads I34 formed on the plunger II5 somewhat below theshoulder I26. Thus by imparting rotative movement-to the actuated sleeveI30, this sleeve may be moved downwardly to clamp the jaws 95 and 96 orupwardly so as to release these laws. Such rotative movement is impartedto the sleeve I30 through meansactuated by the operating handle IOI, andas herein shown such means include a large gear I35, Fig. 10, mounted onthe Plate I10 and meshed with a smaller gear I36 which .is drivinglyconnected to the sleeve I30 so that rotative movement may be transmittedto the sleeve from the gear I36.

. As herein shown the connection between .thegear I36 and the sleeve.I30is afiorded by ahexagonal opening I3Iformed in the gear I36 so as toslidably embrace a complemental hexagonal portion of the outer surfaceof the sleeve I30. Thusrthe sleeve I30 may be rotated, and duringanda'fter such rotation is free for at least a limited amount oflongitudinal sliding movement relative to the gear I36. In the presentinstance the gears I35 and I36 are supported by means which include theplate H0. Thus the gear I35 has a stub shaft I38 secured therein bya'cross'pin I39,'and the stub shaft I38 is extended downwardly intoabearing opening formed in the plate H0. When the stub shaft I38 is inthis position, it is held in place and protected by an upper plate I40which is secured in position by the bolts III. The plate I40 hascircular recesses MI and I42 formed therein to house the gears I35 andI36 respectively, and the gear l36 is centered by a bearing sleeve I43which is formed on the gear and extends downwardly into a bearingopening formed in the plate IIO. Preferably a dust cap I44 is threadedinto the plate I40 about the upwardly projecting end portion of thesleeve I30. The handle I! is connected to the upwardly projecting endI45 of the stub shaft I38 so that by lateral movement of the handle IOI,the gear I35 may be rotated. This rotation is transmitted to the gearI35 and thence to the actuating sleeve I30 for clamping or unclampingthe jaws 95 and 96.

When the work holder 44 is to be moved to its loading position of Fig.13 for loading or unloading of a work piece, the locating structure I iswithdrawn in a downward direction so as to afford the requisite amountof clearance beneath the lower edge of the wall I03, and in accordancewith the present invention this withdrawing movement is accomplished atthe same time as the unlocking of the locking earns 85. Thus, as shownin Figs. 4 and ii, the bearing portion 11 of the carrier 65 has avertical slot I50 extended into its forward face at about the level ofthe locking shaft 18, and this slot I50 is extended into the inside ofthe sleeve 61 and vertically thereof to afford a narrow and relativelyshallow clearance slot I5! in the forward side of the inner surface ofthe sleeve 61. Within this vertical clearance slot I5I, a relativelyshort rack I53 is disposed and is secured to the outer forward surfaceof the sleeve I02 by means including a pair of pins I 54. The rack I53is meshed with a gear I55 which is mounted within the slot I50 upon atransverse supporting pin I56. The forward edge of the gear I55 isengaged with a pinion 151 which is fixed on the locking shaft 18 betweenthe two bearing sleeves 19, and hence it will be clear that the locatingstructure I05 may be operated by rotating movement of the locking shaft18. The arrangement in the present case is such that when the lookingshaft 18 is operated in a counterclockwise direction in Fig. 4 throughan unlocking movement, the gear I55 will be operated in a clockwisedirection as viewed in Fig. 4 and this will cause the locating structureI05 to be withdrawn in a downward direction. Hence when the operatortilts the carrier 65 in a forward direction so as to move the lockingearns 85 into the narrow portion of the slots 84, the locking shaft 18will be held in the same rotative position and the locating structureI05 will be maintained in its lower or retracted position. When thecarrier 65 is again returned to its vertical or operative position shownin Fig. 4, the spring 88 serves to impart clockwise movement to theshaft 18 when the cams 85 have been moved into the enlarged portions 84of the slots 84. This returns the locating structure I05 to its upperposition, as shown in Fig. 4, so that the blank W is in a position tohave the desired heating and forging operations performed thereon. Itwill be observed that the forging stroke of the work holder isaccomplished as herein shown by upward movement of the plunger II5 withrespect to the locating structure I05, and such actuation of the plungerH5 is attained by a piston I60 which is freely mounted within thecylinder 66 for upward actuation when air is admitted through an inletconnection I6I disposed at the lower end of the cylinder 66. When thepiston I60 is thus actuated, a reduced upper end I60 on the piston isdriven through an opening I62 in the bottom plate H1 and with ahammer-like blow against the lower end of the plunger I I5.

The electrodes I00 must, of course, be engaged with the opposite edgesurfaces of the work blank W in order to effect the desired heating ofthe work blank, and yet these electrodes must be separated from the workblank prior to the forging operation in order that the upward movementof the work blank W and the work holder 44 will not cause damage to theadjacent ends of the electrodes. The electrodes I00 are thereforemounted in alignment on opposite sides of the housing 35 forlongitudinal approaching or separating movement, and to this end eachelectrode I00 comprises an outer supporting sleeve I65 which is slidablelongitudinally in a complemental bore I66 formed in the body whichaffords the housing 34, as will be evident in Figs. 5 and 6 of thedrawings. Within each supporting sleeve I65 an insulating sleeve I61 ispositioned and the current carrying member I68 of the electrode isextended through the insulating sleeve I61 and is held in place thereinin a longitudinal sense by threads I69 which engage complementalinternal threads formed within the insulating sleeve I61. The insulatingsleeve is held against rotation with respect to the supporting sleeveI65 by means such as a pair of pins I10 which extend through the sleeveI65 and engage grooves in the opposite outer faces of the insulatingsleeve, as shown in Fig. 8 of the drawings. The current carrying memberI68 of each electrode is formed from a material such as copper which hasa relatively low resistance to the flow of current, but at the ends ofthe electrodes where the work piece W is to be engaged, the electrodesare provided with separately made plates I12 which are made from amaterial such as berylium copper which has a relatively high coefficientof electrical conductivity and a relatively high melting point. The purecopper members I68 are extended beneath the plates I12 as indicated atI13 thereby to provide for conduction of the electricity to the point ofcontact with the work blank W with the minimum of electrical resistance.

Because of the relatively high temperatures which are to be produced inthe work blanks W by the electrical heating means, provision is hereinmade for cooling the electrode I00 constantly during the operation ofthe machine. This is accomplished in the present construction throughthe provision of a bore I15 which is extended inwardly from the outerend of each electrode I00. The bore I15 terminates in spaced relation tothe inner end of the electrode, and a somewhat smaller tube I16 isextended into the bore I15. The tube I16 is supported at its outer endin a modifiedT-fitting I11 which has one enlarged nipple I18 thereofthreaded into the enlarged and threaded end of the bore I15. The tubeI16 is extended through the nipple I18 in spaced relation to theinternal surfaces of this nipple, and is extended into the oppositenipple I19 so as to afford a water tight connection from the nipple I19into the tube I16. The opposite nipple I19 of the T-fitting is arrangedto receive a hose coupling I so that water may enter the hose couplingI80 and pass directly into the tube I16. The tube I16 is so supportedthat its inner end is spaced from the inner end of the bore I15 so thatsuch water may then pass in a reverse direction through the annularpassage formed within the bore I15 and about the tube I'IG. This waterthen enters the end of the nipple I78 about the outside of the tube I15and passes to a lateral discharge opening I82 and out of a hose couplingI83 which is associated with the outlet I82 by means including a nippleI84. Thus a constant flow of a cooling liquid such as water may passinto the hose coupling I80 and through the tube I75 to a point adjacentto the inner end of the electrode and this water may then dischargethrough the coupling I83.

The electrodes I must be actuated in each operative cycle of the machineand the means for accomplishing such actuation are under the presentinvention of such a character that the electrodes are maintained ineither their separated or their active positions until another positiveactuation is imparted thereto. In attaining such operation apair ofactuating arms I80 are provided for the electrodes I00, the actuatingarms I95 being disposed in horizontal positions so as to extend in adirection from front to rear of the machine. The arms I90 are pivoted attheir rear ends on vertical pivot bolts I9I which are extended throughpivot bearings I92 on the rear ends of the arms and downwardly throughspacing members I93 which rest upon the upper surface of the mountingplate 39. The bolts I9I are extended downwardly through the mountinglate 39 and nuts I95 are fixed on lower ends of the bolts to hold thespacing and supporting members I523 in the desired upright positions.The forward ends of the arms I90 are provided with forks I98, as shownin Figs. 3, and 8, and the forks I85 are engaged with transverse groovesI9! formed on the enlarged outer ends of the supporting sleeves I65. Theengagement of the forks I95 with the supporting sleeves I65 is such thatthe sleeves I65 are held against rotation,

cam mechanism 280. which is preferably actuated by piston and cylindermeans. As herein shown these means comprise a cylinder 20I having apiston 232 therein from which a piston rod 203 extends in a forwarddirection. The cylinder 20I is supported by means including a pair ofend plates 2% which, as shown in Fig. 12 of'the drawings, are in thenature of angle plates secured by bolts 265 to upstanding mountingmembers 206 carried on the mounting plate 39. The, mounting of thecylinder 120i is such that the axis of the piston rod 293 ishorizontally disposed in sub stantially the plane of the two arms I90and substantially midway between these two arms. Thus a cam member 210,supported on the for. ward end of the piston rod 203 is adapted toextend between a pair of cam rollers 2I I mounted on inwardly extendingportions 2I.2 of the arms I90, and springs 2I3 extended between thevertical mounting axles 2M of the rollers 2II serve to maintain the camrollers 2 in engagement with the cam 2I0. The cam 2I0 is generallyconical in form, and as shown inv Fig. 3, the cam is disposed so thatthis conical portion tapers in a forward direction. At its forward endthe conical surface merges with a cylindrical dwell surface 2I6, andwhen this dwell surface is disposed between the two rollers 2I I thesprings 2I3 may act to urge the forward ends of the arms I90 together tosuch an extent that the inner ends of the electrodes I00 will engage theopposite edges of a work blank W. When the cam 2I0 is actuated in aforward direction, the conical portion of the cam 2I0 serves to separatethe two arms I90 so as to thereby impart similar separating movement tothe electrodes I00, and at the end of such a forward stroke anothercylindrical dwell surface 2II, which is of a greater diameter than thedwell surface 2I6, is brought into alignment with the cam rollers 2.Thus the arms I90 are maintained in their separated positions, and theaction of the springs H3 is ineffective to cause undesired longitudinalmovement of the cam 2I0 even though the actuating force is removed fromthe rear face of the piston The pressure fluid for actuating the piston202 in a forward direction may be supplied to the rear end of thecylinder 20I by an inlet connection 220 and a similar inlet connection22I is also provided at the forward end of the cylinder 20I forsupplying pressure fluid to the forward end of the cylinder.

The electrical connections to the two electrodes I00 are provided inpart by connecting bands 225 which arev clamped about the conductingmembers I58 adjacent to, the outer ends thereof, and flexible electricwires, preferably in the form of flexible coils 225, are extendeddownwardly and are associated with connector bolts 221. These connectorbolts 22! are extended through opposite ends of an insulating bar 220which, as shown in Figs. 3, 4 and 5,, is extended across the twoportions 36a of the standards just forwardly of the. mounting plate 39,and further electrical connections are extended to the bolts 221 in amanner which will hereinafter be described.

During the heating of a work blank W in the heating chamber 35 it isdesirable to prevent oxidation or other undesirable changes in respectto the, metal of, the work blank, and this. may be accomplished throughthe provision of an inert atmosphere within the chamber 35. I havediscovered however that the atmosphere within the chamber 35 may be ofsuch a character that it would not ordinarily be termed inert, thegoverning factor in this regard being that the atmosphere within thechamber 35 must be such that during the required heating period it willnot cause or permit any undesired change in the metal. Thus, where arelatively short heating period on the order of but two or three secondsis required, I have found that ordinary illumi nating gas may be usedto, provide the necessary protection for the work blank. It will benoted, of course, that such illuminating gas contains carbon, and thatit therefore has a tendency to carburize the blank, but in the shortheating period involved in the use, of the present. machine, suchcarburizing action is negligible, and unob- J'ectionable.

For the purpose of supplying and passing such gas through the heatingchamber 35. an entry passage 230 is provided in one side of the mountingsleeve 45 near the base, thereof, and; as shown in Fig. 5, this entrypassage 230 is arranged to meet a vertical extending groove 23I formedin the inner surface of. the sleeve 45 beneath the shoulder upon whichthe plate 52 rests. If desired, the cross sectional area of the groove23I may be augmented by a matching groove 282 formed in the edges of theplates 52, 53 and 55. The gas may thus enter through the entry passage230 and may pass downwardly into the heating chamber 35, and this gasmay then pass on through the chamber 35 and out of an outlet passagewhich includes a groove 233 and a bore 234. The groove 233 is formed inthe opposite side of the inner surface of the sleeve 46 in the sameposition as the groove 23F, and the bore 234 is extended into the sleeve46 on the left hand side thereof as viewed in Fig. 5. The crosssectional area of the groove 233 may be augmented by a similar grooveformed in a matching relation in the edges of the plates 52, 53 and 55.

Since the present embodiment of the machine contemplates the use of adangerous gas such as illuminating gas to protect the heated workblanks, means must be provided for disposing of such gas after it haspassed through the chamber 35, and this is accomplished under thepresent invention by a burner 236 which is extended upwardly from theoutlet passage 234. Thus by burning the exhaust gases in the burner 236an indicating flame is provided which will inform the operator towhether or not the desired flow of gas is passing through the heatingchamber 35. It will be observed, however, that during the loading andunloading operations the bottom of the chamber 35 will be open, and forthis reason provision is made for shutting off the flow of gas throughthe chamber 35 during the loading and unloading periods. Because of theturning off and on of the gas flowing to the burner 236, a pilot burner23'! is mounted beside the burner 236 and a continuous supply of gas isfurnished from a main source 23% and through a cut-oil and adjustingvalve 239 and a pipe 240 so that the pilot burner 23T may operatecontinuously. Gas is supplied to the inlet passage 239 through a branchconduit extended from the source 238 through a cut-off and adjustingvalve 2 H from which the conduit extends as at 242 to a second cut-offvalve 243. valve 243 to the inlet 239, and during the operation of themachine, the valve 243 is closed whenever the work holder 44 is moved toits loading position and is opened whenever the work holder 44 isreturned to its operating position.

Such operation of the valve 243 is, under the present invention,accomplished automatically, and in the embodiment herein shown suchautomatic operation is attained through operative connection of thevalve 243 with the locking shaft 18. Thus, as shown in Figs. 3, 10, 11,12 and 13, a transmitting shaft 245 of tubular form is pivoted at 246 tothe valve member of the valve 243 and the shaft 245 is extended upwardlyand forwardly and is connected to the shaft 16. In accomplishing suchconnection an annular bearing bracket 24! has one of its ends mounted insurrounding relation upon the left hand end of the locking shaft 18 andis held in position by a bevel gear 248 which is pinned on the end ofthe shaft 18. The other arm of the bearing bracket 24'! has a bevel gear249 mounted thereon so that the gear 49 is meshed with the bevel gear248. The bevel gear 249 is carried upon a shaft 250 which extends intothe sleeve shaft 245 in a slidable relation, and the shafts aredrivingly connected by a pin and slot connection 25] which is best shownin Figs. 12 and 13. Thus when the locking shaft 13 is rotated through anunlocking movement, the shaft 245 is rotated so as to move the valvemember of the A pipe 244 extends from the valve 243 to its closedposition which is shown in Fig. 13 and in which the axis of the pivot246 is disposed parallel to the rocking axis 10 of the carrier 65. Whenthis relationship has been established, the work holder 44 and thecarrier 65 may be tilted forwardly and during such movement the shaft245 pivots about the axis 246 and the shaft 250 is telescoped downwardlyto a greater extent within the sleeve shaft 245 as will be evident upona comparison of Figs. 12 and 13. Thus, as the carrier 65 is unlocked,the flow of gas through the chamber 35 is out off, and because of thefact that the shaft 18 cannot be rotated in a return direction after thework holder 44 has been withdrawn in a forward direction, the supply ofgas to the chamber will necessarily remain cut off until the work holder44 has been returned to its operative position. When this is done thelocking shaft 18 is operated through a locking movement by its spring 88so that the valve 243 is again operated to its open position. The gastherefore flows through the chamber 35 and when this gas reaches theburner 235 it is ignited by the flame which is present at the pilotburner 231,

The pressure air for actuating the piston 202 of the cylinder 2M issupplied and controlled by two different valve means one of whichcomprises a manually operated valve 256 which is mounted on. the forwardright hand portion of the table top 32 as shown in Figs. 1, 2 and 15.The valve 250 has an operating handle 25l which is urged to its righthand closed position as shown in Fig. 16 by means including a spring252. Air is supplied to the valve 260 from any desired source by aninlet pipe 263 and when the valve 260 is opened by movement of the valvehandle 25! to the left in Fig. 16, such air is conducted through v apipe 265 to the forward inlet connection 22! of the cylinder 29!. Thusthe piston 202 is forced to its rearward position shown in Figs. 3 and19 to thereby withdraw the cam member 210 to such a position that therollers 2H are engaged with the dwell surface 2l6 of the cam, When thisis done the springs 2|3 draw the two arms I90 toward each other tothereby move the electrodes I09 into operative engagement with theopposite edges of a work blank W which is supported within the heatingchamber 35. The handle 26! of the valve 260 is then allowed to return ina right hand direction to its closed or out off position wherein it notonly cuts off the supply of air from the inlet 253 but also connects thepipe 265 with a vent pipe 258 so as to permit venting of the forward endof the cylinder 20! when the piston is again actuated to its forwardposition.

Such forward actuation of the piston 202 is desired after the heating ofthe work blank has been completed and prior to the actuation of thehammer or piston Hill, and air is supplied to the rear end of thecylinder 20! under the control of a normally closed cut-off valve 210disposed within the base 3i. The valve 273 is supplied with pressure airby a pipe 2 which is extended from a supply tank 212 located within thebase 3|, and as herein shown this supply tank 2'12 is maintained at asubstantially constant pressure by means of a pressure reducing valve213 which is interposed between pipe sections 214 and 215 which leadfrom a suitable source to the supply tank 212. If desired, a pressuregauge 276 disposed above the table top 32 may be associated with the lowpressure side of the pressure reducing valve 213 in th general mannerindicated in Fig. 17. The outlet or the-valve 210 has a T- iittingZiBconnected-thereto. 'IAwflexible hose coupling 279 connected to onebranchofthe T- iitting is-extended..upwardlythrough the table top and isconnected to the rearinlet 220 of the cylinder 20!. The-other branch ofthe T-fitting 238 is connectedgby a flexible-hose coupling 283 to thelower inlet opening l6l 'of the cylinder 9-3 so that when the valve2l0is opened, pressure air is supplied through'thehose 219*to the rearend of the cylinder land through the coupling hose 280 to the lowerendtof the cylinder 55. The valve 210 has a projecting stem 282 whichmay be pressed inwardly to open" the valve.

The valve operating stem 282 is,-in the present case, actuated bya:s01en0id 283 which ismounted on the top of the supplytank 212 and hasits armature 234 connected to one end of a lever 285. The lever285:is.pivoted:at its intermediate ends on a bracket 286 whichis-carriedon the valve 210, and the other end of i the. lever 285 is arranged forengagement with the valve operating stem 282. Thus, when the solenoid283 is energized, the stem 282 is pressed inwardly and the valve 2Y0 isopened, andlpressure air is supplied to the rear end of the cylinder 2Mand to the lower end of the cylinder'fifi. With the arrangement thusdescribed the rear'end of the cylinder 2M is constantly connectedthrough the hoses 219 and 280 to the lower end 'of the cylinder 9S, andhence when thepiston 202 is actuated in a rearward .direction, the airwithin the rear end of the cylinderl is vented by forcing this air intothe lower end-0f the cylinder Such air tends to lift thepiston or hammerlot, but the rate of flow is such that the piston [20 is not operatedthrough a forging stroke at this time. Hence the air .merelyescapesat arelatively slow rate about the piston I and passes out of exhaustOpenings 288 formed in the sides of the cylinder: 66 adjacent the upperend thereof. This arrangement therefore functions as a dashpot toprevent too rapid-approaching movement of theielectrodes I00.

When the valve 210 is openedto cause sep aration of the electrodes I00and operation of the hammer H50, the present apparatusoperates to attainthe requisite timed relation ofthese operations, for it will be clearthat separation of v the electrodes starts immediately upon-forwardmovement of the cam 2l0, 'while upward-movement of the "work holder doesnot start-until the upward stroke of the hammer l60;is substantiallycompleted. To afiordadditional clearance, however, the portions H3 ofthe electrodes are cut away on a gradual taper lT3Aon'thei1 lower facesas shown in Fig. 5.

The operation of the solenoid '283 is desired only after the heating ofa blank -W has'been completed, and this solenoid-is therefore placedunder the control of timing :mechanism -generally designated as 290 inFig. l9-of-the'drawings. This timing mechanism isdiagrammatically shownin the present instance-and is arranged to start through'its timingcycle, under the control of the manual'valve handle 2Bl 'sothat theoperating cycle of the machine is manually initiated, and such timingcycle is automatically terminated by the timing mechanism 290. Ashereinshown the timing mechanism 290 is mechanical in character and includes atiming shaft 292 upon which a co-nstantlydriven pulley 293 is looselmounted. The pulley 293 is'driven by a belt connection 294 from asynchronous 'motor 295, and when a timing cycle is desired, the

' shaft 292 is connected to the pulley 293 by means such as aone-revolution clutch 298. This clutch may be of general constructionshown in the patent to Gollwitzer, No. 2,265,133, patented December 9,1941. As herein shown, the clutch 295 includes a driving member 291fixed 0n the pulley 293 and-a driven member 298 fixed on the shaft 292for relative sliding movement in a longitudinal direction so that,opposed teeth on the adjacent ends of the driving and driven members may'be'erigaged by movement of the driven member 298 in a left handdirection from the position shown in Fig. 19. The driven member 298 isconstantly urged toward an engaged relation by a spring 299 winchsurrounds the shaft 292 and acts between the driven member 298 and acollar 300 fixed on the shaft 292. The driven-member 298 has a stop pin30I projecting radially therefrom and in the rotation of the drivenmember this pin is adapted to engage a cam surface formed on a stoplever 302 so as to shift the driven member 298 to the right in Fig. 19to thereby disengage the clutch. The stop lever 302 normally ridesagainst the outer surface of the driven member 298 so as to release theclutch at a predetermined point in th rotation of the driven member, andsuch rotation of driven member 298 is stopped at a predetermined pointby engagement of the pin 30l with a stop finger 303 formed on the stoplever 302. The stop lever 302 is pivoted intermediate its ends on apivot 304, and the other end of the stop lever is connected to thearmature 305 of a solenoid 306, so that when the solenoid 306 isenergized the stop lever 302 will be pivoted so as to release the pin30l and permit closure of the clutch 296. This institutes the desiredtiming period or cycle, and during this cycle the solenoid 306 isdeenergized so as to return the stop lever 302 to its active position,thereb to cause the clutch 295 to be open at the end of a one-revolutiontimin cycle.

The electrical elements of the present machine are energized from linewires LI and L2, Fig. 19, which carry a suitable alternating current,The line wire Ll is connected by a wire 3l0 to one terminal of the motor295 while the other terminal of the motor is connected-by wires 3H and3l2 in series to one terminal of a main switch 3l3, the other terminalof which is connected to the line wire L2. Thus when the main switch M3is closed the motor 295 operates continuously so as to thereby renderthe timing mechanism 290 available at any time to initiate'and controlan operative cycle of the machine. Such a timing cycle of the timingmechanism 290 is initiated byenergization 'of the solenoid 305 and tothis end the line wire'Ll is extended so as to connect with one terminalof the solenoid 305. The other terminal of the solenoid 305 isconnected'by a wire 315 to onecontact of a normally open switch 315, theother terminal of which is connected-to the wire 3| l. Thus by closureof the switch 3H3 the solenoid 308 may be energized, and the switch 315'is arranged for operation'by the manual starting handle 25!. Thus, asshown in' Figs. 16 and 19, the starting handle 25! has an arm 3l8 fixedthereto so that it is moved with the handle 20!, and when the handle265i is moved to the left in Fig. 16 a roller 3l9 carried on the arm SIBis arranged to engage a cam surface 320 formed on a switch operatinglever 32I. The switch operating lever 3 is pivoted at 322 on the housin3l6A of the switch'3l6 and when the camsurface 3201s engaged by theroller 319, the lever 32! engages a projecting plunger 324 so as topress the same inwardly of the housing 3l6a and thereby close the switch3| 6. The arrangement of the arm 3|8 with respect to the valve 260 issuch that the roller 3| 9 does not strike the cam surface 320 so as toclose the switch 316 until after the valve 260 has been opened and hascaused rearward actuation of the cam 2m. Thus the electrodes IUD aremoved into contact with the work blank W prior to the time when thetiming mechanism 290 causes the electrodes I to be energized.

The timing mechanism 29!! operates to control such energization of theelectrodes H ll and in addition, the timing mechanism serves to governthe energization of the solenoid 283 which in turn controls theseparation of the electrodes 10!] and the operation of the piston orhammer Hill. In accomplishing such controlling operations the presenttiming mechanism 230 has a pair of cam discs 330 and 33l fixed upon theshaft 292 for rotation therewith. The cam disc 33!! is arranged toactuate and control a normally open switch 332 which serves as theprimary control for energizing the electrodes HID, while the cam disc33! serves to actuate and control a normally open switch 333 whichserves as the primary control for governing the energization of thesolenoid 233.

Such control of the switch 332 by the cam disc 33!] is attained by arelatively long cam lobe 330A formed on the cam disc 330. This cam lobehas its leading edge 330B arranged to engage and actuate the switch 332soon after rotation of the timing shaft .292 is started. The length ofthe cam lobe 3361A is of such a magnitude as to i hold the switch 332closed for the desired heating period, and at the end of this heatingperiod the follower of the switch 332 rides off of the trailing edge33GB of the cam lobe 330A. The

controlling action of the cam 33l on the switch drive the hammer 60through its forging stroke and to maintain the hammer in its upperposition with. the work blank engaged with the die for a short coolingperiod.

The energizing circuit for the electrodes I00 includes a transformer T,the secondary winding 335 of which is connected in circuit with theelectrodes. Thus a wire 335 is extended from one terminal of thesecondary winding 335 and is connected to one of the terminal bolts 22'!while a wire 33l' is extended from. the other terminal of the secondarywinding 335 to the other terminal bolt 22?. With this arrangement the energization of the electrodes Hill is governed by switch means theenergizing circuit of the primary winding 333 of the transformer T. Thusas shown in Fig. 19 a wire 339 is connected from the line wire Ll to oneterminal of the primary winding 338 of the transformer, while a wire 340extends from the other terminal of the primary to one of the contacts ofthe normally open switch 332. The other contact of the switch 332 isconnected by a wire 345 to the wire 33! so that energization of thetransformer T and hence of the ggezctrodes H19 is governed by the timingswitch open position.

The energization of the solenoid 283 is governed primarily by the switch333, but the circuit for the solenoid 283 also includes a safety switch342 which is open at all times except when the work holder 43 is lockedin its operative position. Thus, one contact of the switch 333 isconnected to the wire 339 by a wire thereby to establish circuit to theline wire LI, and the other contact of the switch 333 is connected by awire 334 to one terminal of the solenoid 283.. The other terminal of thesolenoid 283 is connected by a wire 345 to one contact of the switch 342while the other contact of the switch 332 is connected to the wire 33!by a wire 346. The switch 342 is of the mercury tube type and thisswitch is mounted on a holder 34? carried on the outer end of a stubshaft 343 extended through the web portion of the right hand standard36. The stub shaft 348 has a bell crank fixed on the inner or left handend thereof, as viewed in Fig. 11, and this bell crank has a downwardlyprojecting arm 349, Fig. 14, upon which a spring 356 is operative tonormally tend to rotate the shaft 348 in a clockwise direction as shownin Fig. 14. Such rotation is limited by a stop pin 35! which is extendedinwardly from the inner surface of the right hand standard 35 so as tolie in the path of the other arm 352 of the aforesaid bell crank. Whenthe arm. 352 is in the position indicated by dot-dash lines in Fig. 14the switch 342 is in its 2 The switch normally tends to occupy this openposition and is arranged to be closed by the locking shaft is when thisshaft is rotated to its locking position. Thus, as will be evident inFigs. 10, 11 and 1d. the shaft 18 has an arm 355 fixed thereon, as byclamping about the hub of the right hand locking cam 85, and when thelocking shaft 18 is operated in a clockwise direction to the positionshown in Fig. 14, an arm 355 engages the arm 352 to shift the switch 332to its closed position. Hence it will be clear that if the work holderis located forwardly of its operative position or is not properly lockedin this operative position, the switch 342 will be open and it will beimpossible to energize the solenoid 233. When this dangerous conditionexists, the disabling of the energizing circuit of the solenoid 283serves to disable the hammer mechanism of the machine, and hence theparts of the machine cannot be injured by inadvertent operation of thehammer means.

The cooling liquid such as water for cooling the two electrodes IE0 issupplied from a supply pipe 363 which is connected through a valve 35!and a pipe 362, Figs. 2 and 19, to a header pipe 363 which is extendedalong the back of the base 3! as will be evident in Fig. 17 of thedrawings. The valve 36! has an operating handle 384 which is preferablyinterlocked as indicated at 365 with the main switch 3 l3 so that theswitch 3 l3 cannot be closed until the 'valve 355i has been opened. Thisassures that the cooling liquid will be flowing in the electrodes 1 Oilprior to the energization of these electrodes. The header pipe 333 isconnected by flexible hoses 366 and 36! to the respective inletconnectors Mil of the electrode cooling circuits so that a coolant suchas water is supplied to the central tubes i'l't of these electrodes.After such water has passed through these electrodes it is of coursedischarged from the two' connectors I33 and such discharged water orother coolant is carried awa by hoses 378 and

